The transforming growth factor 2 (TGF2) superfamily of growth factors is the largest family of secreted proteins in mammals. These diverse ligands, which are synthesized as prepropeptides and processed to active dimers, function in essentially every developmental and physiologic process. Our HD33438 grant, Analysis of Reproductive Function Using Transgenic Mice, has been funded by NICHD since 1996 and was the recipient of a MERIT award in 2001. Over this funding period, Dr. Matzuk (the Principal Investigator) and his laboratory have been productive leaders in the identification and characterization of the oocyte-secreted TGF2 family members, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15). With the support of HD33438, we have published over 80 papers including a dozen papers in Nature, Nature Genetics, Nature Medicine, Science, and PLoS Biology. Whereas mammalian oocytes were initially postulated to be passengers rather than drivers in ovarian folliculogenesis, we demonstrated that GDF9 is essential for fertility at the primary follicle stage and plays critical roles at the pre-ovulatory follicle stage to regulate cumulus expansion. We also discovered the X-linked BMP15 gene and have characterized its functions in vitro and in vivo. These insights have helped to define the oocyte-somatic cell dialogue in ovarian folliculogenesis. The overall hypotheses of this renewal are that the oocyte-secreted proteins, GDF9 and BMP15, signal through specific ovarian granulosa cell type 1 receptors and downstream pathways to regulate oocyte maturation and fertilization and subsequent embryo development in mice and women and that TGF2 and microRNA pathways are linked in smooth muscle development in the female reproductive tract. The Specific Aims of these proposed studies are: 1) Characterize the relationship of TGF2 and microRNA pathways in the development of oviductal and uterine smooth muscles; 2) Identify the GDF9 type 1 receptor in granulosa cells; 3) Determine the molecular aspects for receptor specificity of the BMP15 and GDF9 ligands; and 4) Study the BMP15 and GDF9 signaling pathways in human granulosa cells. These studies will not only accelerate the pace of research in the Matzuk laboratory but will also accelerate translational research in other United States laboratories including those of our Co-investigators, Drs. Mandy Katz-Jaffe and Thomas Thompson. At the end of this 5-year period, we expect to have unlocked key molecular events that are orchestrated by members of the TGF2family and drive human reproduction and that will ultimately facilitate efforts to optimize assisted reproductive technology procedures for women.